An objective lens drive and an optical pickup apparatus are provided which can be reduced in size. Two tilt coils and two tracking coils are disposed so that among planes defined by the respective coils, a plane perpendicular to a winding direction thereof is parallel to a reference plane defined on a lens holder at a predetermined reference distance or less, and are disposed at such positions as to be symmetrical to each other about a center of gravity of the lens holder. A focus coil is disposed so that among planes defined by the focus coil, a plane perpendicular to a recording surface of an optical disk is parallel to the reference plane at a predetermined reference distance or less relative to the two tilt coils and the two tracking coils.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An objective lens drive comprising: a light-collecting unit for collecting a light beam; a holding unit having a reference plane defined thereon so as to be perpendicular to a recording medium for recording information, for holding the light-collecting unit; a first coil held by the holding unit, for moving the holding unit so that the light beam collected by the light-collecting unit is focused on the recording medium, the first coil being wound around an axis extending in a first direction perpendicular to the recording medium; two second coils held by the holding unit, for moving the holding unit so that a focal point of the light beam collected by the light-collecting unit follows a track formed in the recording medium, each of the two second coils being wound around an axis extending in a second direction parallel to the recording medium and perpendicular to the reference plane defined on the holding unit; two third coils held by the holding unit, for tilting the holding unit so as to tilt the light-collecting unit in accordance with a tilt of the recording medium, each of the two third coils being wound around an axis extending in said second direction; a supporting unit for movably supporting the holding unit; two magnets for allowing the first coil, the two second coils, and the two third coils to be driven; and a base for supporting the supporting unit and the two magnets, wherein the two second coils are arranged so as to be rotationally symmetrical to each other around an axis of symmetry extending in the second direction, but are not plane symmetrical to each other, the two third coils are arranged so as to be rotationally symmetrical to each other around said axis of symmetry, but are not plane symmetrical to each other, and the two second coils and the two third coils are disposed so that among planes defined by a wound wire of the respective coils, a plane perpendicular to said axis of symmetry is parallel to the reference plane defined on the holding unit at a predetermined reference distance or less.
2. The objective lens drive of claim 1 , wherein the first coil is disposed so that among planes defined by a wound wire of the first coil, a plane perpendicular to a recording surface of the recording medium is parallel to the reference plane at a predetermined reference distance or less.
3. The objective lens drive of claim 2 , wherein said axis of symmetry passes through a position obtained by projecting on the reference plane a center of gravity of the holding unit for holding the light-collecting unit, the first coil, the two second coils, and the two third coils.
4. The objective lens drive of claim 2 , wherein the supporting unit supports the holding unit at positions defined by intersection of the supporting unit and a plane at an intermediate position between the reference plane and a plane which is defined by the first coil and parallel to the reference plane at the predetermined reference distance or less.
5. The objective lens drive of claim 1 , wherein, among winding parts of the respective second coils, one winding parts of the respective second coils extending in a direction same as an optical axis direction of the light-collecting unit have outer circumferential surfaces parallel and close to each other.
6. The objective lens drive of claim 1 , wherein, among winding parts of the respective second coils, one winding parts of the respective second coils extending in a direction same as an optical axis direction of the light-collecting unit are disposed on a straight line in a direction same as an optical axis direction of the light-collecting unit.
7. The objective lens drive of claim 1 , wherein, among the two magnets, a first magnet is disposed close to the first coil, among the magnets, a second magnet different from the first magnet is disposed close to the two second coils and the two third coils, and the first magnet is different from the second magnet in at least one of height, width, and thickness.
8. The objective lens drive of claim 1 , further comprising additional two second coils similar to the two second coils and additional two third coils similar to the two third coils, wherein two second coils among the four second coils and two third coils among the four third coils are disposed so as to be rotationally symmetrical to the other two second coils among the four second coils and the other two third coils among the four third coils relative to a plane including an optical axis of the light-collecting unit, the plane being perpendicular to a recording surface of the recording medium and orthogonal to axial lines of the second coils.
9. The objective lens drive of claim 8 , wherein the supporting unit supports the holding unit at positions defined by intersection of the supporting unit and a plane including the optical axis of the light-collecting unit, the plane being perpendicular to the recording surface of the recording medium and orthogonal to axial lines of the second coils.
10. The objective lens drive of claim 1 , further comprising additional two second coils similar to the two second coils and additional two third coils similar to the two third coils, wherein two second coils among the four second coils and two third coils among the four third coils are disposed so as to be rotationally symmetrical to the other two second coils among the four second coils and the other two third coils among the four third coils relative to an optical axis of the light-collecting unit.
11. An optical pickup apparatus comprising: the objective lens drive of claim 1 ; a light source for emitting a light beam; an optical component for converting the light beam emitted by the lights source into a collimated light beam; and a reflecting unit for reflecting toward the light-collecting unit the light beam having passed through the optical component.
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October 24, 2008
February 7, 2012
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